The processing and presentation of endogenous and exogenous antigen by Schwann cells in vitro.

The expression of major histocomatibility complex class II in vitro and in vivo by Schwann cells indicates a potential facultative role of Schwann cells in the presentation of antigen to neuritogenic T cells during inflammatory demyelinating neuropathies. Using a T cell proliferation assay, this study demonstrated that processing and presentation of endogenous and exogenous antigen by Schwann cells influences T cell proliferation. Statistical analysis of proliferation and its relation to processing and presentation of antigen by Schwann cells had not been previously addressed. Different combinations of factors including treatment of cultures (untreated, irradiated or fixed), concentration of exogenous antigen (0 or 40 microg/ml), the presence of interferon-gamma and the timing of exogenous antigen addition influence the proliferation P2-specific, non-mammalian protein ovalbumin-specific T cell lines and naive T cells.

Restimulation of resting autoreactive T cells by Schwann cells in vitro.

This study demonstrates that rat Schwann cells can reactivate resting experimental allergic neuritis generating P(2) and P(2) peptide specific CD4(+) T cell lines. T cell proliferation was significantly greater to P(2) than to P(2) peptide (SP-26) or ovalbumin (OA). Four-level analysis of variance showed that T cell proliferation with endogenous or exogenous P(2) was not significantly different for Schwann cells plus cytokine IFN-gamma (P = 0.5071) unlike P(2) peptide or OA specific T cells (P = 0.0056 and 0.0003, respectively). Untreated Schwann cells were more effective inducers than irradiated or fixed Schwann cells. As stimulated CD4(+) P(2) T cells produce IFN-gamma and TNF-alpha, this could exacerbate blood nerve barrier breakdown that has been increasingly implicated in inflammatory demyelinating neuropathies (IDNs). This would permit entry of antibodies and complement, thereby contributing to the demyelination process. Schwann cell induced reactivation of CD4(+) T cells may therefore play a role in IDNs.

The distribution and abundance of MHC and ICAM-1 on Schwann cells in vitro.

Schwann cells, the myelin forming glial cells of peripheral nerves, have been implicated as having an immunoregulatory role in inflammatory demyelinating neuropathies (IDNs) such as Guillain Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP). We employed rat IFN-gamma, a cytokine released by macrophages and CD4+ T-cells during inflammatory demyelination of the peripheral nervous system, to examine the distribution and abundance of MHC class I, MHC class II and ICAM-1 on Lewis rat Schwann cells and fibroblasts in vitro. MHC class I, class II and ICAM-1 molecules were immunolabelled with 30 nm colloidal gold and observed by scanning electron microscopy. Incubation with IFN-gamma for 24 and 72 h, resulted in the clustering of MHC class I and ICAM-1 on Schwann cells and fibroblasts with MHC class II randomly distributed as single particles. MHC class I and ICAM-1 were upregulated after 24 h incubation in the presence of IFN-gamma, whereas MHC class II was upregulated after 72 h. The difference in the rate of upregulation may indicate differences in the recycling and/or synthesis of these molecules. Changes in distribution such as clustering, in conjunction with the upregulation of these molecules, suggest a role for Schwann cells in the restimulation of specifically primed CD4+ T-cells in IDNs.

An improved protocol for immunogold staining for scanning electron microscopy of cultured cells.

This paper describes an effective protocol for preparing immunogold-labelled cultured cells for high-resolution scanning electron microscopy. The cells examined were rat peripheral nerve Schwann cells and fibroblasts. The protocol employs low concentrations of chemicals and decreased fixation time. The resultant immunohistochemical cell labelling has little or no background staining, while maintaining the morphological integrity of the cell membrane.